Ma, Zhimin
Li, Ditian
Zhan, Siyan
Sun, Feng
Xu, Chaonan
Wang, Yunfeng
Yang, Xinghua
Funding for this research was provided by:
Beijing Municipal Education Commision (KM201310025010)
Article History
Received: 2 February 2018
Accepted: 10 August 2018
First Online: 21 August 2018
Compliance with ethical standards
:
: The Peking University Institutional Review Board approved this study. Since it eliminated all identifiable personal information, it does not belong to studies involving human beings. Consequently, this Board waived the requirement for informed consent and ethical review of the study. (Authorization Code: MJHRFB2014003C).
: The requirement for informed consent was waived for this study.
: The authors declare that no competing interests exist.